Machado 2005.

Methods	Retrospective case‐control study (confirmed influenza versus no influenza) Location and setting: Brazil
Participants	HSCT recipients (CML, acute leukaemia, severe aplastic anaemia, NHL, MM, other) 43 participants eligible to receive influenza vaccination: 19 vaccinated 24 unvaccinated Mean age not reported
Interventions	Influenza vaccination, obtained from review of participants' charts
Outcomes	Confirmed influenza by direct immunofluorescence assay Adverse events
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Non‐random
Allocation concealment (selection bias)	High risk	Non‐random
Incomplete outcome data (attrition bias) All outcomes	High risk	Mortality ‐ no record
Selective reporting (reporting bias)	High risk	The only outcome reported was documented influenza
Other bias	High risk	No control for cancer stage and functional capacity, funding not mentioned, no sample size calculation
Blinding of participants and personnel (performance bias) All outcomes	High risk	Non‐blinded
Blinding of outcome assessment (detection bias) All outcomes	High risk	Non‐blinded